6 Forces in Equilibrium Flashcards
What is a vector?
any physical quantity that has a direction as well as a magnitude
what is a scalar?
any physical quantity that is not directional
What is displacement?
distance in a given direction
what is velocity?
speed in a given direction
what is the resultant force of multiple forces?
the combined effect of multiple forces
How do you find the magnitude and angle of a resultant force?
- magnitude - Pythagoras
- angle - trig
What does resolving a force mean?
splitting a force F into two perpendicular components
What does equilibrium mean?
when the forces acting on an object are balanced so it is at rest or in uniform motion
How do you check if an object is in equilibrium if three forces are acting on it?
- resolve each force along the vertical and horizontal lines
- balance the components along each line
What is a moment?
the moment of a force about any point is defined as the force x perpendicular distance from the line of action of the force
what is the principle of moments?
for an object in equilibrium, the sum of the clockwise moments about any point = the sum of the anticlockwise moments about that point
what is the centre of mass of a body?
the point through which a single force on the body has no turning effect
what is a support force?
When an object is in equilibrium, there is a force equal and opposite to the total downwards force
how do you work out support forces with two supports?
use the moments about each point
what is a couple?
a pair of equal and opposite forces acting on a body but not along the same line
what is the formula for the moment of a couple?
force x perpendicular distance between the lines of action of the forces
what is stable equilibrium?
when a body returns to its equilibrium position when its displaced then released
what is unstable equilibrium?
when a body is displaced and then released, it does not return to its equilibrium position
what is tilting?
when an object is acted on by a force which raises it up on one side
what do you have to consider when looking if an object is going to tilt?
the moments of the force applied to make it tilt and the moment caused by the weight.
when does an object topple?
when it is tilted too far.
this is because as it is tilted more and more, the line of action of the weight passes closer and closer to the pivot and eventually passes beyond the pivot
what is a free body diagram?
a diagram which just shows the forces acting on an object
what is the triangle of forces?
three forces as vectors acting on an object in equilibrium should make a triangle
